PTCA procedures generally include inflation of a balloon in an arterial passage in an effort to clear a flow path for blood by dilating the stenosis. Inflation of the balloon and subsequent deflation and removal of the balloon results in treatment of the stenosis to increase the available cross-sectional area for blood to flow through the arterial passage.
In typical PTCA procedures, a guiding catheter is inserted into the cardiovascular system through the Tee-brachial or femoral arteries, generally under local anesthesia, until the distal tip of the catheter is in a coronary artery and generally positioned adjacent a stenosis. An extensible balloon of a dilation catheter is advanced through the guiding catheter alone or over a previously introduced guidewire until the balloon is positioned across the stenosis. The balloon is then inflated to a predetermined size with a fluid, preferably a radiopaque liquid, to radially compress the inside of the artery wall, thereby dilating the lumen of the artery. The balloon is then deflated so that the dilation catheter can be removed, and blood flow resumed through the dilated artery that now has a larger cross-sectional area to permit a greater volume of blood to flow therethrough.
In typical PTCA procedures, when the balloon of a dilation catheter is inflated in a coronary artery, all flow ceases through the coronary artery. If blood flow ceases for too long a period of time, the part of the heart which that coronary artery serves can begin to suffer from lack of blood, or ischemia. If the balloon remains inflated in the artery for prolonged periods of time, the injury caused by the absence of blood flow can be irreversible in some cases. On the other hand, it has been found that the probability of an artery wall or the stenosis maintaining its dilated cross-sectional area after having been subjected to dilation from an extensible balloon is directly related to the length of time that the balloon is inflated while located across the stenosis. However, the aforementioned potential problems associated with blocking blood flow are increased the longer the balloon is inflated in the artery.
Attempts have been made to produce dilation catheters that perfuse blood through a catheter or balloon when the balloon is inflated to avoid ischemia conditions distally of the balloon. For example, Wijay, et al., U.S. Pat. No. 5,158,540, discloses a perfusion catheter that perfuses blood during the balloon's inflation cycle to allow for longer inflation periods; however, the catheter is extremely complicated structurally and expensive to manufacture.
It is, therefore a general object of the present invention, to provide a brace to impart perfusion attributes to a balloon dilation catheter suitable for PTCA procedures.
Another object of the invention is to provide a modified dilation catheter and procedure of its use for PTCA procedures wherein blood perfuses around the inflated balloon and permits prolonged inflation times for the balloon.
Another object of the present invention is to provide a perfusion brace for a dilation catheter and which is of a relatively simple structure for use in PTCA procedures where blood is perfused distally of the inflated balloon.
Another object of the present invention is to provide a brace for easily converting a standard non-perfusion dilation balloon into a balloon that perfuses blood past the balloon when the balloon is inflated in the artery.
The present invention overcomes the problems associated with the prior art perfusion catheters by providing a perfusion brace on a balloon catheter with a balloon that may be varied between a collapsed condition of a size allowing the catheter to be transported through a body vessel and an expanded condition of a size allowing the exterior surface of the balloon to engage a body vessel wall. The perfusion brace is fixed around the balloon and restricts radial expansion of a portion of the balloon that traverses the length of the balloon while at the same time allowing the remaining portion of the balloon to extend to its full expanded condition. A channel for perfusing fluid past the expanded balloon is thereby formed along the restriction defined by the brace, the channel being further defined by the expanded portions of the balloon.
For a complete understanding of the present invention, reference is made to the embodiments illustrated in greater detail in the accompanying drawings and described by way of example. It should be understood that this invention is not limited to the particular embodiments illustrated herein, but is defined by the appended claims.